Magnetotransport properties of BaRuO 3 : Observation of two scattering rates

Physical Review B - Condensed Matter and Materials Physics. Volume 84, Issue 23, 20 December 2011, Article number 233104.We report results of low-temperature magnetotransport and Hall measurements on single crystals of four-layered hexagonal (4H) and nine-layered rhombohedral (9R) BaRuO 3 that provide insight into the structure-property relationships of BaRuO 3 polymorphs. We found that 4H BaRuO 3 possesses Fermi-liquid behavior down to the lowest temperature (T) of our measurements, 1.8 K. On the other hand, 9R BaRuO 3 was found to show a crossover in the temperature dependence of resistivity around 150 K and the existence of two separate scattering rates at low temperatures. The magnetoresistance in the 9R BaRuO 3 was found to be negative while that in the 4H BaRuO 3 is positive. We propose that local moments may be present in 9R but not in 4H BaRuO 3 , which leads to distinctly different behavior in the two forms. © 2011 American Physical Society